The invention relates to an actuation apparatus for a control flap arranged on the trailing edge of an airfoil of an aircraft. Preferred embodiments of the invention relate to an actuation apparatus for moving the control flap relative to the wing between a stowed position and an extended position with a rotational and a translational component.
To increase lift for takeoff and landing and certain other flight maneuvers, control flaps are used, among other means, which are disposed on the trailing edge of the aircraft wing and, in the manner of a so-called Fowler flap, are displaced in a combined translational and rotational motion between a stowed position, in which they are located near the trailing edge of the wing and substantially in the wing plane, and an extended position, in which they are displaced rearwardly relative to the trailing edge of the wing and angled downwardly relative to the wing plane, and the corresponding intermediate positions.
To control such control flaps, mechanisms are required which must be able, on the one hand, to absorb the very high loads occurring on the flaps and, on the other hand, to execute highly precise movements.
A number of different types of such actuation apparatuses are known in the art.
German Laid Open Publication DE 26 11 918 A1, U.S. Pat. No. 4,702,442 and U.S. Pat. No. 4,434,959 each describe actuation apparatuses for control flaps disposed on the trailing edge of the wing of an aircraft and serving to increase lift. In these apparatuses, two control flaps, here in the form of so-called double-slotted Fowler flaps, are connected in series in the direction of the profile depth of the wing. In the extended position they are spaced apart from each other and from the trailing edge of the wing, respectively, to form a gap allowing the air stream coming from the underside of the wing to pass through. The flaps are held and can be controlled by a mechanism disposed on the load-bearing structure of the wing, which has a plurality of joints and intercoupled scissor-type flat stays and can be driven by a crank drive.
German Laid Open Publication DE 196 47 077 A1 describes an actuation apparatus for a control flap used to increase lift, in which the flap, in the area of its leading end, is flexibly connected with a support carrier, which via guide elements is guided in, and can be displaced along a track provided near the trailing edge of the wing and extending in the direction of the profile depth of the wing. At a force application point located further rearward in the direction of the profile depth, the flap is pivotably coupled by means of a rocker with the trailing end of a support extending in the direction of the profile depth, which also carries the track for the support carrier. When actuated by means of a crank drive, the control flap, on the one hand, is displaced rearwardly on the support carrier and, on the other hand, is angled downwardly, via the rocker.
The prior-art actuation apparatuses have in common that the mechanisms are accommodated in pod-like housings, so-called fairings, which are accommodated below the wing. As the flaps are extended these pods are adjusted downwardly, partly following the combined translational and rotational motion. The pods require a large amount of space and increase the aerodynamic cross-section and thereby the resistance and fuel consumption of the aircraft during cruising, and they reduce the aerodynamic efficiency of the control flap by blocking the airflow between the trailing edge of the wing and the extended flap. They are also a source of irritating noise.
An object of the invention is to provide an improved actuation apparatus.
According to the invention, this object is attained by an actuation apparatus for a control flap disposed on the trailing edge of the wing of an aircraft, wherein the actuation apparatus comprises at least one adjustment unit which is connected, on the one hand, to the load-bearing structure of a wing and, on the other hand, to a control flap, with at least one virtual axis of rotation lying at a finite distance from a plane of the wing. The actuation apparatus includes driving means, with respect to which the structural parts can be displaced in relation to each other.
Advantageous features of preferred embodiments of the actuation apparatus according to the invention are described herein and in the claims.
According to a preferred embodiment of the invention, an actuation apparatus is provided for moving two structural parts relative to each other between a stowed position and an extended position with a rotational motion and a translational motion component. This actuation apparatus has at least one adjustment device with at least one virtual axis of rotation, which is located, in particular, at a finite distance from the plane of the wing profile. The adjustment device is connected with the load-bearing structure of the wing on the one hand and the control flap on the other. The actuation apparatus further has driving means to displace the structural parts relative to each other.
The invention provides an actuation apparatus for a control flap disposed on the trailing edge of the wing of an aircraft. The control flap can be displaced between a stowed position in which it is stowed near the trailing edge of the wing and substantially lies in the wing plane, and an extended position in which it is displaced rearwardly relative to the trailing edge of the wing and angled downwardly relative to the wing plane, and the corresponding intermediate positions. As provided by the invention, the actuation apparatus has a pyramid mechanism arrangement, which is connected with the load-bearing structure of the wing on the one hand and the control flap on the other, with at least one virtual axis of rotation located, in particular, at a finite distance from the plane of the wing profile in relation to which the control flap can be displaced, and driving means for retracting and extending the control flap.
One advantage of the actuation apparatus according to the invention is that it does not require any pods (fairings) to be provided on the underside of the wing, such that aerodynamic resistance, fuel consumption and noise development are reduced. A further advantage is that it has a smaller number of moving parts, which means lower production costs and greater reliability and ease of maintenance.
One embodiment of the actuation apparatus according to the invention provides that the actuation apparatus includes a pyramid mechanism arrangement, which essentially serves to change the distance of the control flap from the trailing edge of the wing, and an adjustment device, which is mechanically coupled to the pyramid mechanism arrangement and essentially serves to adjust the angle of the control flap.
In a preferred embodiment thereof, the adjustment device is formed by a second pyramid mechanism, which is mechanically connected in series with a first pyramid mechanism of the pyramid mechanism arrangement between the load-bearing structure of the wing and the control flap.
In a preferred embodiment of the actuation apparatus according to the invention, the pyramid mechanism arrangement includes a first and a second pyramid mechanism, which are mechanically connected in series between the load-bearing structure of the wing and the control flap.
Preferably, the first and second pyramid mechanisms have virtual axes of rotation that are located at different distances.
A preferred embodiment provides that the first pyramid mechanism, which is arranged closer to the wing, has a more remote virtual axis of rotation than the second pyramid mechanism, which is disposed closer to the control flap.
The more remote virtual axis of rotation can be at infinity.
In the actuation apparatus according to the invention it is preferably provided that the first and/or second pyramid mechanism each have a first leg and a second leg, which at their one end are flexibly interconnected by a common pivot axis and at their other end are directly or indirectly connected with the wing via first end axes and directly or indirectly connected to the control flap via a second end axis.
In particular, it is provided that the first and the second end axis and the pivot axis intersect at a common vertex, which lies on the virtual axis of rotation.
One embodiment of the actuation apparatus according to the invention provides that the first leg of the first pyramid mechanism with its first end axis is connected to the load-bearing structure of the wing at a point which is laterally offset in the direction parallel to the virtual axis of rotation relative to the point at which the second leg with its second end axis is directly or indirectly connected to the control flap by a distance which substantially corresponds to the length of the first leg.
Another preferred embodiment of the actuation apparatus according to the invention provides that the first leg of the first pyramid mechanisms with its first end axis is connected to the load-bearing structure of the wing at a point which, as seen in direction of the profile depth, is substantially aligned in front of the point at which the second leg with its second end axis is directly or indirectly connected to the control flap.
Preferred embodiments of the actuation apparatus according to the invention may provide that the second pyramid mechanism is mechanically connected in series behind the first pyramid mechanism, such that the first leg of the second pyramid mechanism with its first end axis is connected to or shares the second end axis of the first pyramid mechanism, and such that the second leg of the second pyramid mechanism with its second end axis is connected to the control flap at a point which, as seen in the direction of the profile depth, is substantially aligned behind the point at which the first leg with its first end axis is connected to the first pyramid mechanism.
Yet another embodiment of the actuation apparatus according to the invention provides that the actuation apparatus has a single pyramid mechanism arrangement, which serves both to change the distance of the control flap from the trailing edge of the wing and to adjust the angle of the control flap.
Advantageously, the driving means for retracting and extending the control flap is a rotary actuator mechanism coupled to the first pyramid mechanism.
In a preferred embodiment, the rotary actuator mechanism is coupled to and driven by a drive shaft, which substantially extends in the direction of the length of the wing.
A preferred embodiment provides that the second pyramid mechanism is coupled to and driven by the first pyramid mechanism.
In particular, it may be provided that the first leg of the second pyramid mechanism is coupled to or integral with and driven by the second leg of the first pyramid mechanism.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.